Tile images must be square PNGs 144px by 144px. For best results, we recommend using a transparent background, not a background that matches the tile’s color. The tile color can be specified as a hex RGB color using CSS’s #rrggbb notation, via CSS color names, or by the CSS rgb() function.

The next step is associating the badge notification XML to the Web page. IE10 uses the meta tag “application-name” to determine if the Web page supports pinned sites capabilities like notifications and jump lists. To support badge notifications, include a new meta-tag in your markup with the URL of the badge notification XML and the frequency with which Windows should request it. IE checks to see if the “msApplication-badge” meta tag is present on the page at time of pinning, as well as on subsequent launches of the site from the pinned site tile.

The value parameter has two parts: polling-uri (required) and frequency (optional).

polling-uri is the absolute URI from which Windows requests the simple XML document defined above.

frequency is an optional number of minutes between updates and must be one of the following values:
30 (Windows will poll the URI every 30 minutes)
60 (1 hour)
360 (6 hours)
720 (12 hours)
1440 (1 day. This is the default.)
If frequency is omitted or has a value other than one listed above, it defaults to daily updates (1440 minutes).

There has been some feature requests in the module "Pinned Site" that hopes to add Win8 and Win8.1 tile features. I thought the info/code on that page might help kickstart some additions to this module for this issue: